Solar panels are usable too far out and RTGs never become economical

[CaptRobau]

Solar panels are too OP and thus RTGs never become a more economical choice and this needs to change. IRL even the most modern solar panels start becoming less economical than RTGs somewhere around Ceres. The Juno spacecraft to Jupiter is an exception, but that is only due to global shortage of the type plutonium used for RTGs. In KSP solar panels are more economic than RTGs all the way into deep space. Only at Voyager-like distances to Kerbol do RTGs become more useful, which is just insane. While RTGs have their uses in KSP (power generation while flying through an atmosphere and power on the dark side) its intended purpose is not represented at all, which is a shame.

E/t is electricity per ton

[table=width: 500, class: grid]

[tr]

[td]Planet:[/td]

[td]E/t for the OX-4L:[/td]

[td]E/t for the RTG:[/td]

[/tr]

[tr]

[td]Kerbin[/td]

[td]114.286[/td]

[td]9.375[/td]

[/tr]

[tr]

[td]Duna[/td]

[td]110.857[/td]

[td]9.375[/td]

[/tr]

[tr]

[td]Dres[/td]

[td]75.999[/td]

[td]9.375[/td]

[/tr]

[tr]

[td]Jool[/td]

[td]57.143[/td]

[td]9.375[/td]

[/tr]

[tr]

[td]Eeloo[/td]

[td]42.857[/td]

[td]9.375[/td]

[/tr]

[/table]

As you can see, solar panel efficiency needs to be brought way down to even come close to making RTGs as useful as they are IRL.

Edited January 24, 2014 by CaptRobau

[Kasuha]

Solar panels are useless when you're occluded by a planet. Forget to deploy them and your probe is dead. And you mostly need only fraction of what they generate, RTGs are ok for most purposes.

I only use solar panels for ion probes and early on in career when RTG is not available. Apart of that, RTG is the part of choice to me.

[SRV Ron]

Do a Voyager mission and you will soon see that they become useless once you get past Eeloo.

[boomerdog2000]

Do a Voyager mission and you will soon see that they become useless once you get past Eeloo.

If that's the range they have that sounds somewhat appropriate. We have Juno IRL as a solar powered craft out to Jupiter. So as soon as we have planets farther out it sounds like RTGs will become much more useful, in addition to using them on the dark side of planets.

[NWM]

At first - by the capacity/size of batteries and energy consumption of wheels and ligths: one unit of energy ~ 10kJ!

By this both Solar panels and RTG-s are too effective. RTG-s would had 1/10 eneregy production, and the Solar panels would produced so much energy around the Moho, and decreased their productivity by the sqare of the distance from trhe Sun(Kerbol), and also decreased by the athmospere(exponential)

On the other hand, it is true, if you not have ion drivers, you dont need the OX-4L, but the recharge is not working, if the device is not active. The vessels cannot be let to have sunbath.

Yes, solving it would made me more pleased, than most of the stupid ideas in this forum

[Stargate525]

Part of the issue you're ignoring is that there is exactly one power-hungry item in the game; the ion drive. Once I get batteries of any kind, I'm never hurting for power with a single rtg, as there's nothing that requires my 500+ energy storage with enough speed to outweigh my ability to run an orbit and recharge the banks.

I guess what I'm saying is that there needs to be a reason to worry about spending electricity before we really start arguing about relative effectiveness of the different types.

[CaptRobau]

Solar panels are useless when you're occluded by a planet. Forget to deploy them and your probe is dead. And you mostly need only fraction of what they generate, RTGs are ok for most purposes.

I only use solar panels for ion probes and early on in career when RTG is not available. Apart of that, RTG is the part of choice to me.

As I said in the OP the RTGS has some advantages like operating in the dark, but they're are never a necessity as they are in RL. I think that's a shame. Electrically you're never really limited after you unlock the static solar panel early on. At any practical travel distance a couple of those do the trick for almost any mission. If solar power is more realistic, it'd mean the larger solar panels and especially the RTG will be more useful.

Do a Voyager mission and you will soon see that they become useless once you get past Eeloo.

Mentioned that in the OP that they run out around that distance. A Voyager mission is useless in career science-wise though , as there's nothing to be gained beyond Eeloo.

If that's the range they have that sounds somewhat appropriate. We have Juno IRL as a solar powered craft out to Jupiter. So as soon as we have planets farther out it sounds like RTGs will become much more useful, in addition to using them on the dark side of planets.

At Jool distances solar panels produce half the power as they do in Kerbin orbit. In Jupiter orbit the Juno's solar panels produce only 4% of the power they would in Earth orbit, so it's scraping. It's economical because of the global shortage of Plutonium 238 which is needed for RTGs. Otherwise they would've popped on an RTG. A KSP solar panel needs to be at twice the distance of Eeloo to produce as little power as the Juno solar panels do IRL. So even with a lot of new planets out there, solar panels would still be inappropriately powerful.

Part of the issue you're ignoring is that there is exactly one power-hungry item in the game; the ion drive. Once I get batteries of any kind, I'm never hurting for power with a single rtg, as there's nothing that requires my 500+ energy storage with enough speed to outweigh my ability to run an orbit and recharge the banks.

I guess what I'm saying is that there needs to be a reason to worry about spending electricity before we really start arguing about relative effectiveness of the different types.

Its part of a larger problem yes, but this single thing is something that should not be forgotten by the devs when they start to take a look at the power management element.

Edited January 24, 2014 by CaptRobau

[AngelLestat]

Something that I never had the time to look up in the game is: Solar panels produce less energy depeding on how far are from Kerbol (the sun)? According to the inverse square rule?

I am agree that things needs to be balance.. For example.. 1 m2 of solar panel in kerbin orbit it will be nice if produce the same as a solar panels in earth orbit. This would be 1300 w/m2.

Half distance from kerbin to kerbol, would be 5400 w/2, and twice distance from kerbin to kerbol would be 340 w/m2.

Also it would be nice if we had power atenuation due to atmosphere. We just need to put some constant value for each planet, and then calculate due height and that constant how much power we receive.

In this case, we would have different scenaries where solar panels are usefull or not.

Also it will be nice to have some issues with nuclear.

Lets said that the crew needs to be far from the reactor to avoid death by radiation.

Edited January 24, 2014 by AngelLestat

[purpletarget]

The OP table also only addresses power generation of the device itself. It does not however, account for the storage requirements, that is the Battery Mass. The power generation per time can be met by one RTG, and one small solar panel, at a significant mass difference. However, the batteries required for Solar to be useful though eclipse periods are the more significant mass portion of the solar powered systems.

In which case, when looking at just the keep-alive power requirements of a basic probe, without instruments, transmissions, lights, or reaction wheel maneuvering, the mass trade-off happens at ~15 hours. While this isn't too much an issue for orbital ops, there are a decent number of celestial bodies that have night cycles lower than that for landed craft, night capable rovers, and even in orbit, there are more and more requirements for power (ie: Science) that can start drawing enough power to either preclude night ops, or require an RTG to maintain capability.

[Wahgineer]

The solar panel generating as much as it does makes some sense, even as far away as eeloo. Why? because in real life, Earth would orbit out much farther then eeloo. also, the rtgs are meant more for base power (providing a constant supply), while the solar panels help with peak loads (when demand is higher than supply for a short time).

[Themohawkninja]

Efficiency doesn't take into account volume. RTG's take up far less space than all but one of the solar panels. Not to mention the fact that solar panels don't work if you can't see the Sun, nor do they work if you forget to deploy them (with the exception of the singular panel.

[Tex_NL]

Try driving your rover at night. You'll grind to a halt pretty fast as you'll run out of power quickly. Adding a large amount of heavy batteries will give you longer legs but it won't last forever. A similar weight of RTG's will. Or try driving you large rover with solar panels extended on Kerbin, Duna or Eve. The atmospheric drag will rip them of in no time.

RTG's might be outclassed by solar panels when it comes to powering orbital craft. For rovers RTG's are superior by far.

[Kasuha]

Something that I never had the time to look up in the game is: Solar panels produce less energy depeding on how far are from Kerbol (the sun)? According to the inverse square rule?

It depends on the distance but not according to the inverse square rule. It also ends at certain distance (208 Mkm if I'm not mistaken)

Real solar panels also don't follow inverse square rule. At certain irradiation level they become saturated and further increase in irradiation brings only small change. Also below certain level they stop delivering any output, too. The output is also affected by effectivity of the panel and of the convertor.

I am agree that things needs to be balance.. For example.. 1 m2 of solar panel in kerbin orbit it will be nice if produce the same as a solar panels in earth orbit. This would be 1300 w/m2.

1300 W/m2 is the raw insolation. There's no way a solar panel can deliver that, the most effective panels with multilayer technology deliver something like 40%. Of the radiation it is able to process, i.e. not from all wavelenghts. So make it 20%. Maybe.

For the sake of realism you may ask also for reduction caused by atmosphere. ~400 W/m2 raw insolation on earth surface, that is.

[coolitic]

Solar panels are useless imo (there is still no practical way to use ion engines). I ALWAYS use RTG, but, I do think that their price in-game is a bit high even if it contains radioactive substances. (but techincally unless you have many reaction wheels/rover wheels, 1 is enough)

[Nuke]

ive been known to use both solar panels and rtgs together. rtg gives me standby power, and solar handles all the high power stuff. realistically though the rtg is underpowered and too light and too small, and the solar panels are so op its insane. i almost always use rtgs on rovers, often several of them. i kinda wish there were some larger ones (dont go posting links to mods, i already use those).

[CaptRobau]

ive been known to use both solar panels and rtgs together. rtg gives me standby power, and solar handles all the high power stuff. realistically though the rtg is underpowered and too light and too small, and the solar panels are so op its insane. i almost always use rtgs on rovers, often several of them. i kinda wish there were some larger ones (dont go posting links to mods, i already use those).

Well RTGs are used in rovers like Curiosity and landers like Viking, so there's precedent there. I'm not saying that there's no advantages to them at all, I'm just saying that for a lot of circumstances solar panels are OP and thus don't give as much room to RTGs as they should.

[Nuke]

id just like to see rtgs get more love. having a small one for standby power is cool and all, but some of the rtgs they use are pretty damn powerful (some go as high as 3kw* 300w). i dont like to see them get overshadowed (both literally and figuratively) by solar panels.

*that was the russian fission reactor from RORSAT, not technically an rtg

Edited January 25, 2014 by Nuke

[Alchemist]

If it was the inverse square dependency on the distance, you'd probably feel the need for RTG much more...

Back in the good old days when there was no stock electrity I once put a solar powered craft in orbit twice further than Kerbin. Then I looked at power gauges and though: "Power at 25 %? I should turn the craft properly. Wait, it is turned properly! Damn, forgot about a feature I put there myself!"

Edited January 25, 2014 by Alchemist

[AngelLestat]

The solar panel generating as much as it does makes some sense, even as far away as eeloo. Why? because in real life, Earth would orbit out much farther then eeloo. also, the rtgs are meant more for base power (providing a constant supply), while the solar panels help with peak loads (when demand is higher than supply for a short time).

But Kerbol does not have the same diameter than Sun. All scales in KSP are reduced a 1/10 I guess.

But if we forget about scales (that was only to avoid game-engine and gameplay drawback) then you will notice that kerbin attemps to be an analogous system to earth conditions.

It depends on the distance but not according to the inverse square rule. It also ends at certain distance (208 Mkm if I'm not mistaken)

Real solar panels also don't follow inverse square rule. At certain irradiation level they become saturated and further increase in irradiation brings only small change. Also below certain level they stop delivering any output, too. The output is also affected by effectivity of the panel and of the convertor.

So, there in fact KSP reduce power production in solar panels due to distance. Ok.

About the saturation, yeah, I also thought in that, I dint mention to not scare any developer to implement square rule in case it wasn´t implement yet.

1300 W/m2 is the raw insolation. There's no way a solar panel can deliver that, the most effective panels with multilayer technology deliver something like 40%. Of the radiation it is able to process, i.e. not from all wavelenghts. So make it 20%. Maybe.

For the sake of realism you may ask also for reduction caused by atmosphere. ~400 W/m2 raw insolation on earth surface, that is.

Yeah I mistake, I had to said that a 1 m2 panel would receive 1300 w/m2 of radiation. But I use the word produce..

*And for the sake of realism.. I did.. In my post I also mention to incorporate a power reduction due to atmosphere. And each planet with a different parameter due to atmosphere composition..

For example, Eve receive more radiation, but it has a thicker atmosphere and maybe the atmosphere has components that block even more the kerbol light. So to a formule of power reduction due to atmosphere height, we need to multiply that value for a constant between 0 and 1 that will depend on the atmosphere components.

If it was the inverse square dependency on the distance, you'd probably feel the need for RTG much more...

Back in the good old days when there was no stock electrity I once put a solar powered craft in orbit twice further than Kerbin. Then I looked at power gauges and though: "Power at 25 %? I should turn the craft properly. Wait, it is turned properly! Damn, forgot about a feature I put there myself!"

Great, so you did a mod formule about power?

If some day you complete this with more realism than the actual KSP way to calculate.. please post it and share

--------------------------------------------------------------

To have a real radiation lv due to distance, it would help to incorporate some day in the future Solar Sails, or Beamed Sail.

For example, in Beamed Sail you need a laser feed it with a lot of power. This power can be collected if we have graphene composites materials acting like solar panel. The material resist more than 2500 Kelvin degrees, and it does not saturate like normal panels. So this allow us to put this panels at a distance very close to Kerbol (0,03 Au or maybe less), with a efficiency of 70% or 80% like the ones that are already estimated plus a brayton cycle, we could practically produce the power need it to such adventure.

Sun radiance at 0,03 Au it will be 150000 w/m2.

[Alchemist]

Great, so you did a mod formule about power?

If some day you complete this with more realism than the actual KSP way to calculate.. please post it and share

It was back in 0.14-0.15 and it started with me making a one-part satellite with deployable sun-tracking solar panels. Then there was request for separate panels part, then I tried to interface that with a life support plugin... It ended with my plugin becoming the base for most solar panels (with interfaces to most of the electric plugins) before there were stock electric systems.

[InfinityArch]

If you're interested, KSP interstellar makes it so solar panels obey the inverse-square law, more realistic than how it works now.

[coolitic]

I see almost no use in solar panels. A couple RTG's get the job done almost every time. Of course, due to their high price, I guess in career mode I can see why solar panels are better.

[Ravenchant]

They also look far better on your craft when used properly. Besides, for roleplaying reasons one may feel the need to minimize the number of RTGs in close proximity to crew

[Nuke]

rtgs are shielded well enough you can stand next to them without a rad suit. long term exposure may be an issue though.

[coolitic]

rtgs are shielded well enough you can stand next to them without a rad suit. long term exposure may be an issue though.

I think he meant the kerbal's tendency to destroy everything they touch, particularly when messing with the jetpack in space. (Learned that the hard way with solar panels)